Universal power converter with single, shared power transformation circuit

Abstract

A power conversion method and apparatus convert an AC input voltage signal or a DC input voltage signal to a DC output voltage signal suitable for driving a DC load. The power converter includes a first voltage stage coupled to a first pair of input terminals to receive a rectified AC input voltage signal. A second voltage stage is coupled to a second pair of input terminals to receive a DC input voltage signal from a battery source. A transistor drive circuit is connected between the input terminals and the first and second voltage stages. The drive circuit causes energy to be stored in either the first or second voltage stage depending upon whether an AC or a DC voltage signal is applied to the input terminals. The stored energy is released to a third voltage stage to produce a DC output voltage at output terminals coupled to a power supply of a portable device, such as a personal computer.

What is claimed is: 
     
       1. A power converter for converting an input voltage signal to a DC output voltage signal for driving a DC load, said power converter comprising: a first set of input terminals for receiving an AC input voltage signal;   a second set of input terminals for receiving a DC input voltage signal;   a single, shared power transformation circuit directly connected to said first set and said second set of input terminals, said power transformation circuit comprising: a first voltage stage coupled to said first set of input terminals;   a second voltage stage coupled to said second set of input terminals; and   a third voltage stage coupled to said first and second voltage stages for convening said input voltage signal to said DC output voltage signal, said third voltage stage further including a set of output terminals connected to said DC load; and;     a controller driver connected between said first and second set so input terminals and said first and second voltage stages for during a selected one of said first and second voltage stages.   
     
     
       2. The power converter of claim 1 wherein said first voltage stage and said second voltage stage respectively conform to a first primary winding and a second primary winding of a transformer, and said third voltage stage corresponds to a secondary winding connected to said output terminal of said transformer. 
     
     
       3. The power converter of claim 1 wherein said controller driver is a transistor. 
     
     
       4. The converter of claim 1 further comprising: a bridge rectifier connected in parallel with said first input terminals for rectifying said AC input voltage signal.   
     
     
       5. The converter of claim 4 wherein said bridge rectifier comprises a full wave diode bridge rectifier. 
     
     
       6. The converter of claim 1 wherein said AC input voltage signal comprises a 90-270 volt AC signal. 
     
     
       7. The converter of claim 1 wherein said DC input voltage signal comprises a 12 volt DC signal. 
     
     
       8. The converter of claim 3 wherein said controller driver further comprises: first and second transistors coupled to said first and second voltage stages, respectively; and   a current mode pulse width modulated controller connected to said transistors collectively for actuating said transistors between a first power state and a second power state responsive to control signals.   
     
     
       9. The converter of claim 8 wherein said controller driver further comprises: a start-up regulator connected to said modulated controller for starting said modulated controller when said AC input signal is being received at said first input terminals.   
     
     
       10. The converter of claim 8 wherein said control signals comprise a current feedback signal and a voltage feedback signal. 
     
     
       11. The converter of claim 8 wherein energy in the form of current is stored in said first voltage stage when said AC input voltage signal is received at said first input terminals and said transistors are actuated to said first power state. 
     
     
       12. The converter of claim 8 wherein energy in the form of current is stored in said second voltage stage when said DC input voltage signal is received at said second input terminals and said transistors are actuated to said first power state. 
     
     
       13. The converter of claim 8 wherein energy in the form of current is released through said second voltage stage to produce said DC output voltage signal at said output terminals when said transistors are actuated to a second state. 
     
     
       14. The converter of claim 10 further comprising: a feedback voltage generating circuit connected to said controller for generating said feedback voltage control signal.   
     
     
       15. The converter of claim 14 wherein said feedback voltage generating circuit further comprises: an error amplifier for comparing said DC output voltage signal with a voltage reference signal input thereto; and   an optical coupler connected between said error amplifier and said controller for producing said voltage output signal responsive to a signal output said error amplifier.   
     
     
       16. The converter of claim 1 wherein said DC load is a portable personal computer. 
     
     
       17. A power converter for converting an input voltage signal to a DC output voltage signal for driving a DC load, said power converter comprising: a first set of input terminals for receiving art AC input voltage signal;   a second set of input terminals for receiving a DC input voltage signal;   a single, shared transformer comprising a first primary winding directly connected to said first set of input terminals, a second primary winding directly connected to said second set of input terminals, and a secondary winding connected to a set of output terminals, wherein said set of output terminals is further connected to said DC load; and   a transistor drive circuit connected between said first and second sets of input terminals and said primary windings of said transformer for driving a selected one of said primary windings to convert said input voltage signal to said DC output voltage signal.   
     
     
       18. The converter of claim 17 further comprising: a bridge rectifier connected in parallel with said first input terminals for rectifying said AC input voltage signal.   
     
     
       19. The converter of claim 18 wherein said means for rectifying comprises a full wave diode bridge rectifier. 
     
     
       20. The converter of claim 17 wherein said AC input voltage signal comprises a 120-240 volt AC signal. 
     
     
       21. The converter of claim 17 wherein said DC input voltage signal comprises a 12 volt DC signal. 
     
     
       22. The converter of claim 17 wherein said transistor drive circuit further comprises: first and second transistors coupled to said first and second primary windings, respectively; and   a current mode pulse width modulated controller connected to said transistors collectively for actuating said transistors between a first power state and a second power state responsive to control signals.   
     
     
       23. The converter of claim 22 wherein said transistor drive circuit further comprises: a start-up regulator connected to said modulated controller for starting said modulated controller when said AC input signal is being received at said first input terminals.   
     
     
       24. The converter of claim 22 wherein said control signals comprise a current feedback signal and a voltage feedback signal. 
     
     
       25. The converter of claim 22 wherein energy in the form of current is stored in said first primary winding when said AC input voltage signal is received at said first input terminals and said transistors are actuated to said first power state. 
     
     
       26. The converter of claim 22 wherein energy in the form of current is stored in said second primary winding when said DC input voltage signal is received at said second input terminals and said transistors are actuated to said first power state. 
     
     
       27. The converter of claim 22 wherein energy in the form of current is released through said secondary winding to produce said DC output voltage signal at said output terminals when said transistors are actuated to a second state. 
     
     
       28. The converter of claim 24 further comprising: a feedback voltage generating circuit connected to said controller for generating said feedback voltage control signal.   
     
     
       29. The converter of claim 28 wherein said feedback voltage generating circuit further comprises: an error amplifier for comparing said DC output voltage signal with a voltage reference signal input thereto; and   an optical coupler connected between said error amplifier and said controller for producing said voltage output signal responsive to a signal output said error amplifier.   
     
     
       30. The converter of claim 17 wherein said DC load is a portable personal computer.